The present disclosure relates to spectroscopy, and more particularly to transmission Raman spectroscopy. There may be situations in which a substance is encountered, the components of which are unknown. It may not be immediately obvious what components are present in the substance. For example, one might not be able to tell what components a substance contains by simply looking at the substance. Moreover, it might not be immediately obvious whether the substance contains impurities, illicit and/or dangerous components, ingredients of interest, or the like. Thus, it may be convenient or advisable for an investigator to stand off a variable or safe distance from such a substance while performing in situ analysis.